Trunking system of radiodistribution



March 19, 1929. 4 E E, L ME T 1,706,381

TRUNKING SYSTEM OF RADIODISTRIBUTION Originai Filed Jan. 21, 1925 2Sheets-Sheet 1 E. E. CLEMENT March 19, 1929.

2 Sheets-Sheet Original Filed Jan. 21, 1925 M M e P. a a w w P P 2 W 0 w3% 1/ .4/ M z W k r m E {III}. 3 w. w 2 2 a M W [I6 7 N v, M 9/ n. W 2%r 5 m ing transmitted simultaneously,- without Patented Mar. 19, 1929.

UNITED STATES nnwnnn PATENT" OFFICE.

n. CLEMENT, or WASHINGTON, msrarc'r or COLUMBIA; AssIenoR 'ro ED- WARDF. COLLADAY, or WASHINGTON, DISTRICT or COLUMBIA.

TRUNKING SYSTEM OF RADIODISTRIBUTION.

Original application filed January 21,

1926, No. 1,577,108. It relates to systems of.

distribution and has for its 1 radio broadcast object to organize such asystem so that a program may be originated, relayed and distributed overa larger area, unif0rmly and in a systematic and orderly manner toauthorized users or subscribers, who may select any one of a pluralityof programs becomplicated apparatus at the subscribers stations, thetubes used by the subscribers in receiving being all preferably locatedat central points where supervision, maintenance, power supply andcontrol may be centralized under the care of expert operators. In mysaidprior application, a district station is,

described, which distributes the program or programs to a plurality oflocal central sta-' tions, matter to their respective groups. of.subscribers; and the distribution as specifically disclosed is overwire circuits to'the subscribers stations The resent application is notnecessarily limite to a system em ploying a district station,theinvention relating more particularly to the circuit and switchingmeans connected to the subscribers line at the local-central station,-and other features which will sufiiciently appear hereinafter.

\ The invention is applicable to manual, automatic or .cocalledsemi-automatic or automanual telephone systems, and while I shalldescribe herein distribution over the subscribers lines ataudio'frequency. only, it will be understood that superaudio frequenciesmay be employed as well, by providing the necessary tuned device at thecentral station, and the necessary detector instrument at thesubscribers station. Such a change is within the scope of any personskilled in this art, after reading the description of my system, and istherefore within the scope of the invention.

My invention is illustrated in theaccompanying drawings, in which:

Fig. 1 indicates diagrammatically-the telephone exchange portion and thebroadcast which in turn distribute the broadcast distributing portion ofa subscribers central station forming part. of my system.

. Fig. 2 is adiagram showing an arrangement of circuits and apparatusaffording selection of a plurality of programs.

Referring to the drawings in detail andfirst to F ig. 1, this shows theessential circuits of an ordinary telephone exchange system in which J Jare line terminal jacks forming the terminals of telephone lines leadingto stations to be interconnected such as the subscriberhlstation A. Thecentral ofiice' terminals of each line are provided with the usual linerelay L, line lamp L and cut-oft relay L. Where service is to be metereda recording meter M is also in dividually associated with the line. Inad dition to the usual line terminal, multiples 1, 2 and 3, representingmultiples of the tip,

sleeve and test or cut-oft circuits, respec-;

tively, I provide a fourth conductor 4 leading from a contact on theline relay along with the multiple conductors 1, 2 and 3 to thebroadcast distributing system ,diagrammed in Fig. 2.

Referring to Fig. 2, a selective switch S is provided, stepped aroundby'means of an 'electromagnet 420, controlled through front contacts 310by the relay 42 which is included in the line circuit of battery B whenthe contacts of theline switch 9 are closed by the radio operatorfiTheselective switch S contains bank contacts ss' s connected to separatebusses 27-28 (carrying No. 1 pro- 1925, Serial No. 3,861. Divided andthis application filed February 19, 182G. Seria1 No. 89,411.

gram), 270- 280 (carrying No. 2 program),

and 2700-2800 (carrying N o. 0 or announcements). 'The switch S does notneed to-be restored to zero, and may be left always inthe last positionto which it has been moved, since the wires 25-26 leading to the wiperarms .9 of the switch are cut off at the relay contacts 2824 when theapparatus is in disuse. The No. 1 and No. 2 program busses are connectedto the output circuits of broadcast relay receiver's 29-290respectively, and

the announcement bus 27002800 is connected to a local distributingapparatus or amplifier with a microphone The announcement set as a wholeis shown sym- '.bolically, only at AS. This position or line at the key63, after inserting the plug P in the jack J These short closures flashboth the telephone and the radio switchboard lamps L (Fig. 1) and 36(Fig.

2).' Connection is established by the radio operator inserting theplug10in the jack 9, or closing the equivalent switcln It may be mentionedin passing that any form of switch may be substituted for the jack 9,even to a relay controlled from a keyboard position by theoperator,without departing from r the invenion. Divers forms of switeges suitablefor this purpose will occur to th skilled in the art, such as for eX-amp'ljez i a key switch of the general type of opera ors ringing andlistening key, having pivoted lever and a rocking wedge passing up anddown between the pairs of contact springs, to open and close, them. Sucha switch may have practically any desired number of contacts, andrequires no separate plug to operate it. The additional contacts areavailable for a number of purposes, including the cut-off of batterycurrent from the magnet 420 when the parts are in disuse, which shouldbe done as a matterof good practice, although not necessarily a part ofthe invention. 1

The subscribers line having been thus connected with the central oilicewires 1-2,

the relay 42 is included therein, and comes under thecontrol of thesubscriber. Since his line circuit-remains closed after signal ing atthe key 63, the relay 42 is energized and closes all its contacts 310,34, 24, 23 and 351. This connects the input or grid side of the linetube 37 to the switch wipers s and also closes the filament circuitthrough battery F. The three pairs of bank contacts ss-s represent asuitable numberto contain allthe program busses, and if it be desired touse a circle of contacts greater in number than the, number of busses,then the latter may be repeated several times in passing around thecircle. The switch wipers are left where they stand without restoring,so that when the subscriber has become connected through the tube 37tothe switch S he is immediately .on some bi'1 s.- Kit is a program busand he desires to select some particular item, he can by means of hiskey 63 propel the switch arms 8 until they come 'in contact with thebank contacts 8 connected to the announcers bus 2700-2800, 'and bylistening, he will hear ,a continuous announcement of the items-thenupon the bus, the items to follow, the numbers or call letters of thestations from which the said I consider this separate announcement bus,

corresponding to an information operators position, to be lmportant aswell as novel and original with myself, and shall claim the sameaccordingly. 'Having ascertained what program and what 1tems he des resto hear, the subscriber is able to start from- .scrves a double purpose,being also the zero bus from which the program busses: are counted. Ifthe subscriber has a loud speaker, and desires some particular item forwhich he has to wait, he may leave his switch connected with theannouncers bus untllthe time for 'making connectlon ar- "rives, and inthe meantime will receive all the announcements with such matters of entertainment and information as may be intercollated therebetween. Thismeans that during the entire broadcasting period, the announcements willbe going on, interpersed with comments, explanations, etc. may be addednews items and the like if desired, but I think it preferable to havethese on' a separate program bus leaving the 'announcers bus to fulfilthe functions of an information operator only.

I have shown herein in Fig. 1 a meter 'connected to the test or cut-offwire 3, and

for telephone recording this would be operated in the usual manner. Formetering theradio. service, I have shown in Fig. 2 the commutator andhigh voltage generator To these adapted to meter operation, in a manner1 familiar to those skilled in the art. generator is-only connected whenthe relay 42 is energized and the commutator closes the circuit, whichoccurs at intervals during the timethe subscribers line is connectedThis I to the radio bus or busses, but it is to be un- 'derstood thatwhere 'there is selection of program, there should also be selection ofa charging rate corresponding thereto; which means thatthere would be aseparate meter metering may beemployed .for this purpose withoutdeparting from the scope of my invention.

It should be stated .in closing thatwhile I have developed herein aspecific arrangement of the apparatus and circuits for the pur-' posesstated, there are a number of modifications which I contemplate andshall not. describe herein specifically, because they will form thesubject matter" of separate 'applications. I wish to state hereinhowever,

that according to one modification, the line the visible signal to'theradio operator that 7 tube to and over the line circuit to the sub-- andreceive audio frequency waves.

he desires radio connection.

While I have herein described and illustrated the. use of audiofrequencies for distribution to the subscribers over-their wired linecircuits theinvention is not limited to such frequencies,- but mayemploy also superaudio frequencies, so longas they are suitable for linetransmission. .In the-wvork heretofore done by- Major General. Squierand others, frequencies ranging from, 25'to kilocycles per second havebeen found suitable for this purpose. In order to make suchfrequencies-available for distribution among the subscribers in thepresent system, the connections from the central station receiving andrelay distributing apparatus remain practically the same as thosedescribed and shown in Fig. 2, the input or grid circuit of theindividual line tube 37 also remaining' the same; The repeating coilconnection to each line-must either be supplemented or replaced howeverby a filter connection, preferably permanent, which will permitsuperaudio frequency currents to be transmitted from the plate circuitofthe scribersstation, while the battery current from the battery B willsimultaneously flow over the subscribers line for signaling and talkingpurposes of the subscriber. Atthe subscribers station, complementarycon'nections must bemade, and a detector radio set must be connected toreceive superaudio currents over the line, while, the telephone elementsare connected, preferably in parallel, to receive the battery currentand transmit Such an arrangement is shown as to its principles inLetters Patent granted. me January 6, 1925, No. 1,522,362, to whichreference is had for further explanation of the principles involved.

The words telephonic relay used in the claims hereinafter are-to beunderstood as meaning a relay including as one element a vacuum tube orthe e uivalent thereof for relayingpotential and current variations suchas those generated in accordance with sound waves, said currentvariations being adapted to act upon mcans to reproduce the originalsound waves.

What I claim is: 1. Ina system of broadcast distribut on, a telephonecentral station, having subscr bers them,- a plurality -of broadcastbusses at the central station, telephonic relaymeansof the typedescribed atthe central statlon, 1n-

dividual to. each subscribers-line, a rotary step-bystep selector'switch having a set substationswith wire lines interconnecting 1 ofwipers arranged to successively'engage a plurality of sets ofco'ntactsin repeating cycles, different sets of contactsbeing connected with saiddifferent broadcast busses,v

means at the central office for connecting said switch to a line whencalling, and controlling ineans at the subscribers substation forsteppingsaid switch forward.

2. In a system of broadcast distribution, a

telephone central station, having subscribers" substations with wirelines interconnecting them, a plurality of-broadcast busses at thecentral station, telephonic relay means of the type described at thecentralstation, in

dividual to each subscribers line, each subscribersindividual-telephonic relay having selective switching means whereby itmay be connected to said busses one at a time in succession and inrecurring'cycles, and

-means for controlling said switc ring means from its associatedsubstation. Y 3. The system claimed in claim all but one of thebroadcast busses are permanently connected during operation tobroadcasting, means to supply programs,

and anajnnouncers transmitter and assoc1- ated apparatus permanentlyconnected during operation to the remaining bus, to furnishannouncements relating to the programs supplied by the other busses.

2 in which i 4: The system'claimed in claim 2 in which" the switch is anon-restoring or uni-directional switch and dlsconnection is effectedbetween the switch and the input side of the telephonic relay means.

5. The system claimed in claim 2, with means at the central station forconnecting a supervisory relay in series with a subscribersline, saidsupervisory relay being responsive to current changes in the subscribersline to connect and disconnect the switch from 1 the first mentionedtelephonic relay' means.

6. The system claimed in claim 2', having a relay controlling theselective switching means, a vacuum tube amplifier as said telephonicrelay' means, and a repeating coil between said tube and the line, saidrelay, tube, and coil being associated together as a working group orunit, and having the input and output circuits of a group controlled bythesubscriber.

'7. Albroadcasting exchange system, comprising a central stationandsubscribers stations,- with line wires interconnecting them,

a plurality of switching busses or terminals at the'central station,means to supply different programs thereto, and a selective relay andamplifier set for each line compr1smg a unidirectional non-restoringswitch having a pairjof wipers engaginga plurality of pairs of bankcontacts in sequent al order and in recurring cycles, circuitconnections from saicl bank contacts to said switching. busses orterminals, circuit connect ons from Send wipers tothe input slde of saidamplifier, other circuit connections from the outputsideo'fsaidamplifier to terminals-of the-associated line, and meanscontrolled over the line by the subscriber to actuate and to stop-saidswitch at will, ,for the purpose of selecting a desired program or ofdiscon-- necting the line from the program busses, saidmeans also-actingto control the program transmission circuits between. sald switchcontacts and the input side of saidamplifier;

8. In a system of to'said busses respectively, subscribers lines andmeans-including a vacuum tube relay for connecting said switch to aline, 'with controlling means at the subscribers station for steppingsaid switch a selection of the class described; a plurality of programbusses, a step by step switch containing bank contacts connectedstepping its wipers and for connecting'the same tothesubscribers line,together wi-thra. unidirectional vacuum relay included insaid lineconnection and also controlled by the subscriber. V I

10. A system of the class described as- 'ing a plurality of programbusses, subscribers lines, a step by step switch containing bankterminals of said program busses and having a pair of wipers cooperatingtherewith, a program repeating relay between said wipers and a,subscribers line, meansbe tween the said repeating relay and the linefor connectingsaid relay and the switch to line, and contact meansbetween the switch and said repeating" relay controlled by. thesubscriber for connecting and disconnecting said switch to and fromsaid'repeatingrelay and thereby to and'from the line.

- In testimony whereof I hereunto afiix A signature.

i EDWARD ii; EMENT,

